There are many watches listed in the private forum that many of us wouldn't normally see in the wild, online or anywhere. If the member doing the listing is relegated to the dealers forum, a forum that many of us don't visit often, then those oft not seen watches won't be seen.
This isn't even about sales, but for people who like the history of watches and seeing the rare, unusual or scarce those watches getting lost in a sea of Rolex and Speedmasters won't help anyone looking for something different.
I've lost count the number of times I've been contacted about a watch I've listed and the member wasn't even looking for that particular watch but saw the listing and felt intrigued enough to PM me. Sometimes they buy, many times they don't, but we always end up having a great discussion about the watch.
I know Speedmasters are sacrosanct here and God forbid anyone bump into the pedestal they rest on, but it's nice to open up the sales forum and have a
holy hell! moment when you see something different.